<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>margin失效情况</title>
	<style>
		.table-cell {
			margin: 40px;
		}
	</style>

</head>
<body>
<span style="margin: 40px">margin:40px，水平元素垂直margin无效</span>

<span class="table-cell">span.table-cell margin无效</span>
<div class="table-cell">div.table-cell margin无效</div>
</body>
</html>